1. Field of the Invention
The present invention relates to an apparatus and method for processing produce and more particularly, to exposing produce to an atmosphere having an effective amount of chlorine dioxide gas in a treatment chamber to reduce microorganisms present on the produce.
2. Description of Related Art
Consumers are currently consuming more fresh produce for health and nutrition reasons, with a 27% increase in fresh produce consumption in the United States from 1970 to 1993. Most popular among consumers are minimally processed and refrigerated (MPR) fruits and vegetables that satisfy the need for convenience and longevity. However, fruits and vegetables can serve as vehicles for almost any foodborne pathogenic microorganism. The usual sources of pathogen contamination are from irrigation or wash water, fertilizers of animal waste and municipal biosolids, infected operators, and operation of facilities with poor sanitation. There have been numerous reports of foodborne outbreaks associated with contaminated foods. Outbreak and incidence of pathogens, such as enterotoxigenic Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., Shigella spp., Cyclospora, and hepatitis A virus, have been attributed to consumption of lettuce, cantaloupe, celery, tomatoes, cabbage, alfalfa sprouts, mushrooms, cucumbers, potatoes, radishes, raspberries, onions, carrots, zucchini, peppers, broccoli, apple cider, and orange juice.
Washing with chlorinated water (50-200 ppm chlorine) is widely used to sanitize whole fruits and vegetables as well as fresh-cut produce on a commercial scale. However, its effectiveness is limited in reducing the population of microorganisms (less than 2 log colony forming unit, hereinafter CFU) on fruits and vegetables. Moreover, environmental and health organizations have expressed concerns with the by-products from chlorine reactions with organic materials, such as chloroform, carbon tetrachloride, chloromethane, and others, generally known as trihalomethanes (THMs) that have been implicated as carcinogens that can lead to kidney, bladder, and colon cancer. Food processors are concerned about the possibility of future regulatory constraints on the use of chlorine as a sanitizing agent. Furthermore, other aqueous sanitation treatments such as hydrogen peroxide, peroxyacetic acid, trisodium phosphate, ozone, chlorine dioxide, and other combinations have been reported, but are not that effective in reducing pathogens on produce surfaces (<3 log). Therefore, highly effective antimicrobial technologies that reduce pathogens on produce to a greater than 3-log reduction are needed.
Gaseous chlorine dioxide (ClO2) treatments can be an alternative antimicrobial for the elimination of pathogens on fruits and vegetables. ClO2 in both gaseous and aqueous phase is a strong oxidizing and sanitizing agent that has broad and high biocidal effectiveness. It has been reported to effectively inactivate bacteria, including pathogens, virus, bacterial spores, and algae. It has about 2.5 times the oxidation capacity of chlorine. ClO2 maintains its bactericidal activity far longer than chlorine. It is also less reactive than chlorine with organic compounds, and its use is preferred where high organic loads are encountered. Advantages of ClO2 over chlorine also include lack of odor and taste, effectiveness at low concentration, nonconversion to chlorophenols which result in residual smells and flavors, ability to remove chlorophenols already present from other sources, and inability to form harmful chloramines and THMs. Aqueous ClO2 has been approved by FDA for use in washing fruits and vegetables in an amount not to exceed 3 ppm residual ClO2. However, the effectiveness of aqueous ClO2 to decontaminate fruits and vegetables is limited and no more than 2 log reductions have been reported.
An object of the present invention is to provide an apparatus and method of processing produce to reduce microorganisms thereon in a manner that overcomes the disadvantages of traditional processing.